Network control apparatus and method

ABSTRACT

A network controller is connected to a peripheral device and to a communication line. The network controller receives a data packet from a management apparatus via the communication line. The network controller identifies a variable to be processed by the network controller and a variable to be processed by the peripheral device in the received data packet. The network controller assembles a data packet with the variable to be processed by the network controller and a data packet with the variable to be processed by the peripheral controller. The network controller sends the data packet with the variable to be processed by the peripheral controller to the peripheral device and causes the peripheral device to process the sent data packet. The network controller processes the data packet with the variable to be processed by the network controller.

This application is a divisional of application Ser. No. 09/859,499,filed May 18, 2001, now U.S. Pat. No. 6,947,964, the contents of whichare incorporated by reference herein.

FIELD OF THE INVENTION

This invention relates to a network controller mounted on a networkdevice such as an image processing device having a network communicationfunction, and to a network control method.

BACKGROUND OF THE INVENTION

Image processing devices such as network-capable printers, scanners andcopiers are becoming increasingly popular at a rapid rate as networkinfrastructures are built.

These network-capable image processing devices are classified into twotypes, namely (1) a type in which a network function is incorporatedwithin the image processing device, i.e., a type in which a networkcontrol function (network controller) is incorporated as part of thecontroller of the image processing device, i.e., and (2) a type in whichthe network function is incorporated as an extension of the imageprocessing device, i.e., a type in which network support is provided byinserting a control device having a network control function (networkcontroller) into an expansion slot or connector of the image processingdevice. Both types of image processing devices are so adapted that theperipheral device such as a printer or scanner is connected to thenetwork controller that is connected to the network.

These network-capable image processing devices are required to have notonly the original communication function for communicating print data orscan data but also a configuration management function andtroubleshooting management function possessed by a network manager, anetwork information management function and functions for supportingadditional functions. The configuration management function is forconfiguring the network system and managing addresses and resources. Thetroubleshooting management function is for detecting network systemfailures, analyzing and reporting the failures and effecting recovery.The network information management function is for performing networkmanagement, namely management of network load and management ofperformance. An example of an additional function is a function forconfiguring another peripheral processing device connected via thenetwork.

A Simple Network Control Protocol (SNMP) is utilized to implement thesefunctions. Management information in a network device is managed in theform of a database referred to as a Management Information Base (MIB).In SNMP, an SNMP-equipped network manager acquires or sets the values ofMIB variables (described later) by an agent which manages each networkdevice. This allows the above-mentioned functions to be implemented.

FIG. 14 is a conceptual view illustrating the structure of an MIB. Asshown in FIG. 14, the MIB has a tree-like data structure in which allnodes are uniquely numbered. The numbers in the parentheses in FIG. 14are node identifiers. For example, the identifier of a node 1401 in FIG.14 is 1. Since the identifier of a node 1402 is 3 and this issubordinate to node 1401, it is written 1.3. Similarly, the identifierof a node 1403 is written 1.3.6.1.2. Such an identifier of a node isreferred to as an object identifier, and each node is referred to as anMIB variable.

In FIG. 14, a node 1404 is one at the vertex of an object group referredto as a standard MIB with which a device managed by SNMP is equipped asa standard. The details of the structure of an object subordinate tosuch a node are stipulated in RFC1213 Management Information Base forNetwork Management of TCP/IP-based Internets: MIB-II.

A node 1405 is one at the vertex of an object group referred to as aprinter MIB with which a printer managed by SNMP is equipped as astandard. The details of the structure of an object subordinate to sucha node are stipulated in RFC1759 Printer MIB.

A node 1406, which is referred to as a private MIB, is one at a vertexwhere an enterprise or organization, etc., defines its own MIB. A node1407, which is referred to as enterprise extension MIB, is one at avertex where an enterprise among private MIBs implements its ownextension. For example, “1602” is assigned to Canon, Inc. as anenterprise number in order that it may define itself. A node 1408, whichis a vertex for defining Canon MIB as Canon's own MIB, is situated underthe node 1407 signifying an enterprise. The object identifier of thevertex node of Canon MIP is 1.3.6.1.4.1.1602.

An agent is incorporated within an image processing device that is anetwork device or is mounted on a network controller externallyconnected to the image processing device. A network controller is anexternally attached network interface card, by way of example. Themanagement information (MIB) also is managed by the network controller.If a network device is an image processing device having multiplefunctions, the database of the MIB of the peripheral device connected tothis network device, e.g., the database of a printer MIB orhost-resource MIB, also is managed in the network controller.

By virtue of this arrangement, a network device can be made the objectof management by an SNMP-equipped network manager. In accordance withSNMP, a network manager can acquire information concerning, or changethe status of, a controlled network device belonging to the samecommunity as that of the network manager. For example, a network managercan send a network device a message containing desired MIB variables,can acquire a character string being displayed on the liquid crystaldisplay device of a printer, and can change the default paper-feedcassette.

In such case the network controller in the network device that hasreceived a message analyzes the content of the message. If the contentof the message is acquisition of information specific to the peripheraldevice connected to the network controller, then the network controlleracquires information from the pertinent peripheral device via a specificcommunication interface between itself and the peripheral device. Thenetwork controller further converts the acquired information to a formatdecided by SMNP and then responds to the network manager.

Thus, in the prior art, the network controller must manage also the MIBof the peripheral device that is connected to it. For example, in a casewhere a plurality of peripheral devices have been combined, as in themanner of a printer and scanner, all of the MIBs relating to theseperipheral devices must be managed by the network controller.

Consequently, in a case where a single network controller is capable ofbeing connected to multiple peripheral devices, it is required that thenetwork controller manage all of the MIBs relating to these peripheraldevices. For example, there are instances where a network controller isconnectable to different model printers A and B, and there are occasionswhere a network controller is connectable to a printer, scanner andfacsimile machine all of which provide different functions. In suchcases it is required that all of the MIBs relating to the connectableperipheral devices be managed by the network controller. A problem whicharises is that the network controller needs to be furnished with a verylarge-capacity memory in order to store these databases.

Another problem is that since communication interfaces between thenetwork controller and the peripheral devices connected to it arespecific to the peripheral devices, the network controller must supportall of these communication interfaces.

If in such case a peripheral device connectable to a network controlleris added on anew, the network controller itself or the control softwareexecuted by the network controller must be updated in order to supportthe interface between the network controller and the new peripheraldevice.

SUMMARY OF THE INVENTION

Accordingly, an object of the present invention is to provide a networkcontroller that does not need to be equipped with a large-capacitymemory to store a management information database.

Another object of the present invention is to provide a networkcontroller in which it is unnecessary to support a plurality ofdifferent communication interfaces for communicating with respectiveones of a plurality of peripheral devices.

A further object of the present invention is to provide a networkcontroller in which when a peripheral device is newly added onto thenetwork controller, the added peripheral device can be supported merelyby adding on a subagent that controls the management information on theside of the peripheral device.

According to the present invention, the following objects are attainedby providing a network device connected to a network and having aplurality of controllers, comprising: a plurality of databases disposedin distributed fashion on respective ones of the plurality ofcontrollers and storing management information relating to respectiveones of the controllers; and a plurality of agents distributed on theplurality of controllers; wherein each of the plurality of agents hasmeans for communicating with one another, means for executingdistributed processing of messages issued from a network manager, andmeans for generating responses to these messages.

Preferably, at least one agent among the plurality thereof functions asa master agent and the other agents function as subagents, and each ofthe agents communicates with one another using a network manager thatmanages the network, a protocol for management information exchangebetween the network manager and the network device.

Preferably, the master agent has means for separating a message issuedfrom a network manager into a first message containing managementinformation to be processed by the master agent, and a second messagecontaining management information other than this managementinformation; response generating means for generating responseinformation with regard to the first message; and means for notifyingsubagents of the second message.

Preferably, the master agent has means for receiving response messagessent back from the subagents; reconstruction means for reconstructing aresponse message, which is to be sent back to the network manager, fromthe response messages and the response information that has beengenerated by the response generating means; and means for sending theresponse message, which has been reconstructed by the reconstructionmeans, back to the network manager.

Preferably, each subagent has means for separating a second message,which has been received from the master agent, into a third messagecontaining management information to be processed by the subagent and afourth message containing management information other than thismanagement information; response generating means for generatingresponse information with regard to the third message; and means fornotifying other subagents of the fourth message.

According to another aspect of the present invention, there is provideda network controller connected to a peripheral device and to acommunication line, comprising: receiving means for receiving data froma management apparatus via the communication line; discriminating meansfor discriminating the data, which has been received by the receivingmeans, as data to be processed by the network controller and data to beprocessed by the peripheral device; and processing means for sending theperipheral device, and causing the peripheral device to process, datathat the discriminating means has discriminated as being data to beprocessed by the peripheral device, and for processing data that thediscriminating means has discriminated as being data to be processed bythe network controller.

The network controller preferably further comprises holding means forholding information relating to the network controller, wherein theprocessing means processes the data using the information held by theholding means.

The network controller preferably further comprises connecting meanscapable of being connected to a plurality of peripheral devices, whereinthe discriminating means discriminates, with regard to each connectedperipheral device, data to be transmitted to and processed by theperipheral device.

Preferably, a peripheral device connected to a communication line viathe network controller comprises: receiving means for receiving datafrom a management apparatus via the network controller; and processingmeans for processing data, which has been received by the receivingmeans, upon referring to a database holding information relating to theperipheral device.

According to another aspect of the present invention, there is provideda network device connected to a communication line and including anetwork controller and a peripheral processing unit, the networkcontroller having receiving means for receiving data from a managementapparatus via the communication line; discriminating means fordiscriminating the data, which has been received by the receiving means,as data to be processed by the network controller and data to beprocessed by the peripheral processing unit; and first processing meansfor sending the peripheral processing unit, and causing the peripheralprocessing unit to process, data that the discriminating means hasdiscriminated as being data to be processed by the peripheral processingunit, and for processing data that the discriminating means hasdiscriminated as being data to be processed by the network controller;and the peripheral processing unit has receiving means for receivingdata that the discriminating means has discriminated as being data to beprocessed by the peripheral processing unit; and second processing meansfor processing data, which has been received by the receiving means,upon referring to a database holding information relating to theperipheral processing unit.

Preferably, the network controller further has holding means for holdinginformation relating to the network controller per se, wherein the firstprocessing means processes the data using the information held by theholding means.

Preferably, the network controller further has connecting means capableof being connected to a plurality of peripheral processing units,wherein the discriminating means discriminates, with regard to eachconnected peripheral processing unit, data to be transmitted to andprocessed by the peripheral processing unit.

According to another aspect of the present invention, there is provideda device controller externally connected at two ends, comprising adatabase; means which, if a message received from upstream containsmanagement information corresponding to an entry in the database, is forgenerating response information by processing the management informationin accordance with the message; means which, if the message containsother management information, is for generating a second messagecontaining this management information and transmitting the secondmessage downstream; and means for reconstructing a response message bycombining the response information with the second message received fromdownstream, and transmitting the response message upstream.

Other features and advantages of the present invention will be apparentfrom the following description taken in conjunction with theaccompanying drawings, in which like reference characters designate thesame or similar parts throughout the figures thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating an arrangement of a master agent andsubagent;

FIG. 2 is a diagram illustrating the software module structure of amaster agent;

FIG. 3 is a diagram illustrating the software module structure of asubagent;

FIG. 4 is a diagram illustrating the hardware structure of a networkcontroller;

FIG. 5 is a flowchart illustrating the flow of control of networkmanagement information;

FIG. 6 is a diagram illustrating a procedure for analyzing a variablebinding;

FIGS. 7A and 7B are flowcharts illustrating control flow of a process A;

FIG. 8 is a flowchart illustrating packet reconstruction of process A;

FIG. 9 is a flowchart illustrating control flow of a process B;

FIGS. 10A and 10B are flowcharts illustrating control after receipt ofprocess-B response acquisition packet;

FIG. 11 is a diagram showing an arrangement having one master agent andN-number of subagents;

FIG. 12 is a diagram illustrating an example of the configuration of anetwork system in an embodiment of the invention;

FIG. 13 is a block diagram of a network device in this embodiment; and

FIG. 14 is a diagram showing an MIB tree structure.

DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment

<Network Configuration>

FIG. 12 illustrates an example of a network that includes a printer 1201connected to the network by a network controller in accordance with thepresent invention.

The network, which has an open architecture, has the printer 1201connected thereto by a network interface card (NIC) 102. The networkinterface card 102 is connected to a local area network (LAN) 100 via aLAN interface such as an Ethernet interface 10Base-2 having a coaxialconnector or a 10Base-T having an RJ-45 connector. The printer 1201 andNIC 102 may be separated or integrated. In this embodiment, the NIC 102shall also be referred to as a network controller 102.

A plurality of personal computers such as 1203 and 1204 also areconnected to the LAN 100 and are capable of communicating with the NIC102 under the control of a network operating system. One of the personalcomputers, say personal computer 1203, can be used as an SNMP-equippednetwork manager (SNMP manager).

Further, a file server 1206 is connected to the LAN 100 and managesaccess to files that have been stored in a large-capacity (e.g., 10 GB)network disk 1207. A printer server 1208 manages printing performed bylocally connected printers 1209 a, 1209 b or printing performed by aremote printer 1205. Other peripherals (not shown) also may be connectedto the LAN 100.

The personal computers 1203 and 1204, which are implemented by ordinarypersonal computers, can each generate data files, transmit the generateddata files to the LAN 100, receive files from the LAN 100 and displaysuch files and/or subject them to processing.

<Structure of Printer 1201>

FIG. 13 is a block diagram showing how the NIC 102, printer 1201 and LAN100 are connected. According to this embodiment, the printer 1201 isconnected to the LAN 100 via the NIC 102, which is the networkcontroller. The NIC 102 is connected to the LAN 100 via a LAN interfaceand to the printer 1201 via a device interface controller (referred tosimply as an I/F controller) 104. Provided on the NIC 102 andinterconnected via an internal bus are a microprocessor 401 forcontrolling the NIC 102, a ROM 402 for storing the operating program ofthe microprocessor 401, a RAM 403 used as a work area when themicroprocessor 401 executes a program, and a peripheral control 407through which the NIC 102 and I/F controller 104 exchange data. Aprogram whereby the NIC 102 operates as an SNMP agent (a master agent,described later) has been stored in the ROM 402. The microprocessor 401operates in accordance with the program stored in the ROM 402 and usesthe RAM 403 as a work area.

A microprocessor 151 in the I/F controller 104 accesses data in the NIC102 via the peripheral control 407 provided in the NIC 102. Themicroprocessor 151 in the I/F controller 104 controls the operation of aprinter controller 107.

The printer controller 107, which has a printer engine 1072, controlsthe printer engine 1072 using the microprocessor 1071 and implements thefunction of a subagent, described later.

<Structure of Agent in Printer 1201>

FIG. 1 is a diagram showing a functional structure that best expressesthe characterizing features of the SNMP master agent in the networkcontroller 102 of the present invention and the characterizing featuresof the subagent in the printer 1201. The network controller 102 andprinter controller 107 are connected via the device interface controller104. A master agent 101 executes processing in the network controllerand a subagent 106 executes processing in an image processing device,which here is the printer controller 107. In FIG. 1, the left side ofthe image processing device interface controller 104 is the master agent(network controller) and the right side is the subagent (imageprocessing device).

In FIG. 1, the SNMP master agent 101 is placed in the network controller102. The lower-order layer of the SNMP master agent is constituted bythe NIC controller 102, a protocol stack 103, the device I/F controller104, and a network database controller 105 for managing networkinformation. In this embodiment, the SNMP master agent 101 manages anMIB-II, an AppleTalk MIB and, among vendor-specific private MIBs, an MIBobject relating to communication control (a management information MIBobject). These MIBs shall be referred to collectively as an MIB database1051.

The MIB-II includes groups referred to as a “system” group, whichprovides generally settings information, and an “interface” group, whichindicates types of network interfaces, etc. An object identifier isassigned to each of these groups as well. The AppleTalk MIB is an objectfor providing information and setting parameters relating to AppleTalk,which is one network system. The private MIB has content which, say, themanufacturer of the NIC 102 itself assigns to the NIC.

The SNMP subagent 106 is placed in the image processing device (here aprinter). In this embodiment, the SNMP subagent 106 is placed in theprinter controller 107. The lower-order layer of the SNMP subagent 106is constituted by the printer controller 107, the device I/F controller104, and a device database controller 108 for managing a databaserequired in the printer. In this embodiment, the SNMP subagent 106manages a host resource MIB, a printer MIB and, among vendor-specificprivate MIBs, an MIB object relating to the printer.

The printer MIB is an object for providing general information relatingto the printer. The private MIB includes content which, say, themanufacturer of the printer itself assigns to the NIC. The host resourceMIB provides information concerning resources of a host computer.

The MIB objects managed by the database controllers 105, 108 in thenetwork controller 102 and printer controller 107, respectively, areobjects that are capable of being managed by an SNMP manager. Since eachMIB object corresponds to a resource possessed by a network device, theSNMP manager can manage each of these network resources in accordancewith SNMP. These groups of MIBs shall be referred to collectively as MIBdatabases.

<Agent Structure>

FIG. 2 is a diagram illustrating the software module structure of theSNMP master agent 101. The blocks constructing the SNMP master agent 101will now be described. Specifically, a packet send/receive controller202 controls the sending and receiving of SNMP packets to and from theprotocol stack. A BER decoder/encoder 203 executes the decoding ofencoded receive SNMP packets and the encoding of transmit packets. AnSNMP packet parser 204 analyzes the content of SNMP packets. Amaster-agent packet generator 205 separates the content of a packet intopackets for the master agent. A subagent packet generator 206 separatesthe content of a packet into packets for a subagent. An MIB databasemanagement unit 207 manages an MIB object ID, which is detected by theSNMP packet parser 204, and mapping information of a processing modulecorresponding to this ID. A method routine controller 208 controls amethod routine group prepared for each object. A subagent I/F controller209 controls communication with a subagent. A GetResponse packetgenerator 210 generates a response packet processed by the master agent101. An SNMP-packet reconstruction controller 211 reconstructs an SNMPpacket, which is to be sent back to the network information manager,from a GetResponse packet of the master agent and a GetResponse packetthat has been sent back from a subagent.

FIG. 3 is a diagram illustrating the software module structure of theSNMP subagent 106. The blocks constructing the SNMP subagent 106 willnow be described. Specifically, a master-agent I/F controller 302controls the sending and receiving of SNMP packets to and from themaster agent 101. An SNMP packet parser 303 analyzes the content of SNMPpackets received from the master agent. An MIB database management unit304 manages an MIB object ID, which is detected by the SNMP packetparser 303, and mapping information of a processing module correspondingto this ID. A method routine controller 305 controls a method routinegroup prepared for each object. A GetResponse packet generator 306generates a response acquisition packet processed by the subagent 106.

<Hardware Structure of Network Controller>

FIG. 4 illustrates the hardware structure of the network controller 102according to this embodiment. A 32-bit RISC chip is used as the CPU 401according to this embodiment. However, this does not impose a limitationupon the invention and any type of CPU may be used. A flash ROM 402holds program execution code and a database that includes an MIB managedby the network database controller 105. An area that is part of the ROM402 is used as a non-volatile memory area and is utilized to storeparameter data and configuration information, etc., that has been set bythe user.

A RAM 403 is used as a work area. In this embodiment, execution code anda database table that have been stored in the flash ROM 402 are copiedto the RAM 403 at start-up. Execution of the program code begins whenthe copying operation is completed.

A LAN physical layer controller (PHY) 405 is connected to Ethernet via aconnector 406. A LAN controller 404, which is of the bus-master type,acquires the bus privilege by arbitration with the CPU 401 usingsend/receive as the event trigger. The LAN controller 404 executessend/receive of data, independently of the CPU 401, in a send/receivebuffer reserved in the RAM 403.

The peripheral control 407, which is an ASIC for controllingcommunication with a peripheral device such as a printer, has a 32-KBdual-port RAM. The arrangement is such that data is communicated withthe peripheral device via the device I/F controller 104 using this DPRAMmemory area.

This embodiment is described taking a printer as the example of aperipheral device connected to the network. As described in FIG. 13, thehardware structure of the printer is a CPU, ROM, RAM structure, similarto that of the network controller 102., and has an arrangement (notshown) that is independent of the control system on the side of thecommunication controller. In addition to this arrangement, the printeris equipped with resources, e.g., a printer engine, for performing afunction specific to the printer. The CPU executes a predeterminedprogram, thereby controlling these resources and implementing an SNMPsubagent.

The software that controls the master agent shown in FIG. 2 is stored inthe flash ROM 402 of FIG. 4, and the software for controlling thesubagent is stored in a ROM on the side of the device interfacecontroller 104, which is the peripheral device.

<Packet Processing by Agent>

The control flow of software that has been stored in each of these ROMswill now be described.

FIG. 5 and FIGS. 7 to 10 illustrate the control flow of a master agentand subagent in a network controller according to this embodiment.

An SNMP packet issued from the SNMP manager 1203 on the network isreceived by the packet send/receive controller 202 of the master agent(step S501). Since the SNMP packet has been encoded in accordance withthe BER stipulation, it is decoded in the BER decoder/encoder 203 of themaster agent (step S502). The decoded SNMP packet is analyzed in theSNMP packet parser 204 in accordance with the definition in ASN.1 (stepS503). The SNMP master agent 101 obtains the version, community, PDUtype, request ID and variable binding from this packet (step S504).

FIG. 6 is a diagram illustrating the format of a packet (referred to asPDU: Protocol Data Unit) used by SNMP as well as a procedure foranalyzing a variable binding 601. The packet includes the SNMP version,the community indicating the group constituted by the SNMP manager andagent, the PDU type indicating the type of PDU of the packet, therequest ID, which is used for comparing a request and response, and thevariable binding 601, which specifies objects and the values thereof.The variable binding 601 is obtained by combining one to a plurality ofelements in each of which the MIB object identifier (variable name) andthe value thereof constitute a set.

The variable binding 601 is analyzed in the SNMP packet parser 204 (stepS510). If the result of analysis is that a variable name N not beingmanaged by the MIB on the side of the master agent has been detected inthe variable binding 601 (“NO” at step S505), the position Nx of thevariable name is stored and the variable name is deleted from thepacket.

The deleted variable N and its value Nv are packetized again, as anobject to be processed on the side of the subagent, in the form of asubagent SNMP packet in subagent packet generator 206 based upon thepreviously stored version, community, PDU type and request IDinformation (step S506).

Since variable names are given in a hierarchical structure, as shown inFIG. 14, matching with variable names in an MIB is easy to perform. TheSNMP manager manages an MIB, which the agent of each network devicemanages by an MIB view, and accesses only a variable that is beingmanaged by the MIB view. Accordingly, a variable which is contained inthe variable binding but which is not being managed by the master agentis judged by the master agent to be an MIB that is being managed by asubagent.

On the other hand, a variable being managed by a master agent isprocessed by the master agent and therefore the variable is packetizedanew by the master-agent packet generator 205. As a result, variables(objects) managed by the master agent are reconstructed into amaster-agent packet 602, and variables (objects) not managed by themaster agent are reconstructed into a subagent packet 603, as shown inFIG. 6. With regard to fields other than the variable binding, fieldsother than those to be changed by packet reconstruction are maintainedas is, which is the case with packet length. Control after separation ofa packet into the master-agent and subagent packets differs dependingupon the PDU type (step S507). That is, a process A (FIGS. 7A, 7B and 8)is executed (step S508) if the PDU type is GetRequest/GetNextRequest,and a process B (FIGS. 9A, 9B and 10) is executed (step S509) if the PDUtype is SetRequest.

<Processing of GetRequest Packet>

FIGS. 7A. 7B and 8 are flowcharts for describing the control flow ofprocess A. The master agent determines whether a packet to be issued toa subagent exists (step S701). If the decision rendered is “YES”, asubagent SNMP packet generated by the subagent packet generator 206 isissued to the subagent via the subagent I/F controller 209 (step S702).

The master agent successively reads out variable-and-value combinationsin the variable binding of the master-agent SNMP packet (step S703),searches the MIB database 1051 using the MIB database management unit207 (step S704), acquires address information of an address at which amethod routine corresponding to a variable has been stored (step S705)and subsequently executes the relevant processing in the method routinecontroller 208 based upon this address information (step S706).

If notification of abnormal end is received from the method routinecontroller 208 after execution of the above-described processing (stepS707), processing is suspended without waiting for completion ofexecution of the overall variable binding, the GetResponse packetgenerator 210 is notified of the error status and index value, aGetResponse packet is generated (step S708) and the master agent thenwaits for issuance of a GetResponse from the subagent side (step S709).

On the other hand, if notification of normal end is received from themethod routine controller 208 (step S707), processing identical withthat of steps S703 to S706 is applied to the next combination ofvariable and value. The same processing is executed until the end of thevariable binding list is reached (step S711).

If a packet has not been issued to a subagent, there will be no responsefrom a subagent and therefore the master agent need not wait for apacket at step S709. The same holds true for step S1006 in FIG. 10A.Further, if a master-agent management object is not contained in apacket received from the SNMP manager, there is no processing to beexecuted at steps S704 to S711. In such cases, therefore, the masteragent either generates a packet having a header only or does notgenerate a packet at all at step S708. The same holds true for stepS1021 in FIG. 10A as well.

If an error does not occur, the master agent generates a GetResponsepacket (step S708) upon the completion of all processing and waits forissuance of a GetResponse from the subagent side (step S709).

On the side of a subagent that has a subagent SNMP packet via themaster-agent I/F controller 302 (“YES” at step S712), the subagent, in amanner similar to the master agent, successively reads outvariable-and-value combinations in the variable binding of the subagentSNMP packet (step S713), searches the MIB database 1081 using the MIBdatabase management unit 304 (step S714), acquires address informationof an address at which a method routine corresponding to a variable hasbeen stored (step S715) and subsequently executes the relevantprocessing in the method routine controller 305 based upon thisinformation (step S716).

If notification of abnormal end is received from the method routinecontroller 305 after execution of the above-described processing (“YES”at step S717), processing is suspended without waiting for completion ofexecution of the overall variable binding, the GetResponse packetgenerator 306 is notified of the error status and index value, and aGetResponse packet is generated (step S718).

The generated GetResponse packet is reported to the master agent via themaster-agent I/F controller 302 (step S719).

If notification of normal end is received from the method routinecontroller 208 (“NO” at step S717), processing identical with that ofsteps S713 to S716 is applied to the next combination of variable andvalue. The same processing is executed until the end of the variablebinding list is reached (step S720). Thereafter, a GetResponse packet isgenerated in the GetResponse packet generator 306 (step S718).

The generated GetResponse packet is reported to the master agent via themaster-agent I/F controller 302 (step S719).

Upon receiving the GetResponse packet from the subagent via the subagentpacket generator 206, the master agent combines this packet with theGetResponse packet generated by the master agent to thereby reconstructthe GetResponse packet in the SNMP-packet reconstruction controller 211.

FIG. 8 is a flowchart for describing the flow of GetResponse packetreconstruction. Here the master agent checks the content of theerror-status fields in the GetResponse packets generated by respectiveones of the master agent and subagents.

If the error status of a GetResponse packet that has been generated bythe master agent indicates an error (“YES” at step S801), then the valueof the error index is converted to the value in the received originalpacket by the packet reconstruction controller (step S802).

At this time the variable binding is not included in the GetResponsepacket in conformity with the atomic rule.

At the moment the conversion processing is completed, BER encoding isperformed by the BER decoder/encoder 203 (step S803), after which theGetResponse packet is sent back to the SNMP manager by processingexecuted in the packet send/receive controller 202.

If the error status of the GetResponse packet received from the subagentindicates an error (step S805), then the value of the error index isconverted to the value in the received original packet by the packetreconstruction controller 211 (step S802).

At this time the variable binding is not included in the GetResponsepacket in conformity with the atomic rule.

At the moment the conversion processing is completed, BER encoding isperformed by the BER decoder/encoder 203 (step S803), after which theGetResponse packet is sent back to the SNMP manager by processingexecuted in the packet send/receive controller 202 (step S804).

If the error status is indicative of no error for both the master agentand subagent (step S806), the variable bindings in the GetResponsepackets of the master agent and subagent are rearranged in an orderidentical with that of the original packet stored at step S504 and arereconstructed into a single GetResponse packet in the SNMP-packetreconstruction controller 211 (step S807).

The reconstructed GetResponse packet is subjected to BER encoding in theBER decoder/encoder 203 (step S803), after which the GetResponse packetis sent back to the SNMP manager by processing executed in the packetsend/receive controller 202 (step S804).

The process A regarding packets for which the PDU type isGetRequest/GetNextRequest is completed through the processing describedabove, after which the system again waits for receipt of an SNMP packetfrom the SNMP manager.

<Processing of SetRequest Packet>

FIGS. 9, 10A and 10B are flowcharts for describing the control flow of aprocess B in a case where the PDU type is Set Request.

As shown in FIG. 9, the master agent successively reads outvariable-and-value combinations in the variable binding of themaster-agent SNMP packet (step S901), acquires, through use of the MIBdatabase management unit 207, address information of an address at whicha method routine corresponding to a variable has been stored (step S903)and subsequently executes the relevant processing in the method routinecontroller 208 based upon this address information (step S904). In thiscase, each method routine evaluates only the validity of each value tobe set, and processing for changing the values of each MIB object tospecified values is not executed at this time.

If notification of abnormal end is received from the method routinecontroller 208 after execution of the above-described processing (stepS905), processing is suspended without waiting for completion ofexecution of the overall variable binding, the GetResponse packetgenerator 210 is notified of the error status and index value and aGetResponse packet is generated. If an error occurs in the process onthe side of the master agent, an SNMP packet is not sent to the subagentside. With regard to the GetResponse packet that has been generated, thevalue of the error index is converted to a value in the receivedoriginal packet by the SNMP-packet reconstruction controller 211 (stepS1001).

The reconstructed GetResponse packet is subjected to BER encoding in theBER decoder/encoder (step S1002), after which the GetResponse packet issent back to the SNMP manager by processing executed in the packetsend/receive controller (step S1003).

If notification of normal end is received from the method routinecontroller 208 (step S906), processing identical with that of steps S901to S904 is applied to the next combination of variable and value. Thesame processing is executed until the end of the variable binding listis reached (step S907). A GetResponse packet is generated after allprocessing has been completed (step S908).

FIGS. 10A and 10B are flowcharts illustrating the control flow aftergeneration of a GetResponse packet by the master agent. At the momentgeneration of the GetResponse packet is completed, the master agentdetermines whether a packet to be issued to a subagent exists (stepS1004). If the decision rendered is “YES”, the subagent SNMP packet thatwas generated at step S506 is issued to the subagent via the subagentI/F controller 209 (step S1005). The master agent then waits from theGetResponse from the subagent (step S1006).

Upon receiving the subagent SNMP packet via the master-agent I/Fcontroller 302 (“YES” at step S1007), the subagent, in a manner similarto the master agent, successively reads out variable-and-valuecombinations in the variable binding of the subagent SNMP packet (stepS1008), searches the MIB database 1081 using the MIB database managementunit 304 (step S1009), acquires address information of an address atwhich a method routine corresponding to a variable has been stored (stepS1010) and subsequently executes the relevant processing in the methodroutine controller 305 based upon this address information (step S1011).

In this case, each method routine evaluates only the validity of eachvalue to be set, and processing for changing the values of each MIBobject to specified values is not executed at this time.

If notification of abnormal end is received from the method routinecontroller 208 after execution of the above-described processing (stepS1012), processing is suspended without waiting for completion ofexecution of the overall variable binding, the GetResponse packetgenerator 306 is notified of the error status and index value and aGetResponse packet is generated (step S1013). The generated GetResponsepacket is reported to the master agent via the master-agent I/Fcontroller 302 (step S1014).

If notification of normal end is received from the method routinecontroller 305 (step S1015), processing identical with that of stepsS1008 to S1011 is applied to the next combination of variable and value.The same processing is then executed until the end of the variablebinding list is reached (step S1016). The subagent again successivelyreads out variable-and-value combinations in the variable binding,acquires, through use of the MIB database management unit 304, addressinformation of an address at which a method routine corresponding to avariable has been stored and subsequently executes the relevantprocessing in the method routine controller based upon this addressinformation. In this process, the subagent changes the values of eachMIB object to specified values (step S1017). Upon completion of thisprocessing, the subagent generates a GetResponse packet in the subagentpacket generator 206 (step S1013) and reports this GetResponse packet tothe master agent via the master-agent I/F controller 302 (step S1014).

Upon receiving the GetResponse packet from the subagent via the subagentI/F controller 209, the master agent reconstructs the GetResponse packetin the SNMP-packet reconstruction controller 211.

If the error status of a GetResponse packet received from a subagentindicates an error (step S1018), the GetResponse packet is discarded bythe SNMP-packet reconstruction controller 211 (step S1019) and the valueof the error index in the GetResponse packet sent back from the subagentis converted to a value in the received original packet (step S1001). Atthis time the variable binding is not included in the GetResponse packetin accordance with the atomic rule.

At the moment conversion processing is completed, BER encoding isperformed by the BER decoder/encoder controller (step S1002), afterwhich the GetResponse packet is sent back to the SNMP manager byprocessing executed in the packet send/receive controller (step S1003).

If the error status of the GetResponse packet received from the subagentis indicative of no error (step S1020), the master agent againsuccessively reads out variable-and-value combinations in the variablebinding, acquires, through use of the MIB database management unit 207,address information of an address at which a method routinecorresponding to a variable has been stored and subsequently executesthe relevant processing in the method routine controller 208 based uponthis address information. The master agent in this process changes thevalues of each MIB object to specified values (step S1021).

At the same time, the variable bindings in the GetResponse packets ofthe master agent and subagent are rearranged in an order identical withthat of the stored original packet and are reconstructed into a singleGetResponse packet in the SNMP-packet reconstruction controller 211(step S1022).

The reconstructed GetResponse packet is subjected to BER encoding in theBER decoder/encoder 203 (step S1002), after which the GetResponse packetis sent back to the SNMP manager by processing executed in the packetsend/receive controller 202 (step S1003).

The process B regarding packets for which the PDU type is Set Request iscompleted through the processing described above, after which the systemagain waits for receipt of an SNMP packet from the SNMP manager.

As described above, an MIB database is divided into one for a masteragent and one for a subagent, the master-agent MIB database is held by anetwork controller and the subagent MIB data is held by a peripheraldevice connected to the network controller, whereby memory resourcesthat are necessary to store a network information management databasecan be distributed. As a result, it is no longer to necessary to provideone agent with a large-capacity memory.

Further, communication of information can be implemented between themaster agent and the subagent by using a protocol identical with acommunication protocol (SNMP) specified between a network manager and anetwork-capable image processing device (a printer in this embodiment).As a result, it is unnecessary for the network controller to be equippedwith a plurality of protocol control means for the purpose ofcommunication between the network controller and peripheral devicesconnected thereto. That is, if the master agent described in thisembodiment is mounted on a network controller and a peripheral deviceconnected thereto is equipped with a subagent and a database thatincludes the requisite MIB and a specific MIB, then a network can bemanaged. Since the content of processing by the subagent is similar tothe content of processing by a conventional agent, mounting the subagentis easy. Furthermore, in a case where a peripheral device is added to anetwork controller anew, the new peripheral device can be made anadditional object of management merely by adding on network managementinformation (an MIB database) concerning this peripheral device and thesubagent that controls this peripheral device, without modifying the MIBdatabase with which the network controller is equipped.

Other Embodiments

In the first embodiment, a mode in which a printer is adopted as theimage processing device (peripheral device) is illustrated. However, theimage processing device is not limited to a printer. More specifically,if the device is a scanner, a facsimile machine, a copier or an imageprocessing device having these multiple functions, and if the device iscapable of being equipped with the subagent functions described in thefirst embodiment, then the device can be managed through a proceduresimilar to that of the first embodiment merely by connecting it to anetwork controller (NIC) equipped with a master agent.

The first embodiment illustrates an example in which an NIC, namely anetwork controller, is inserted into an external expansion slot of aprinter. However, this does not impose a limitation upon the invention.If the arrangement is one in which a network controller and thecontroller of a peripheral device are logically independent of eachother, the present invention can be implemented even in a case wherethese controllers are physically constructed of the same hardware or onthe same board.

In the first embodiment, a network controller and a printer controllercommunicate using their own hardware-implemented interfaces. However, nomatter what communication means these interfaces use, such as generallyemployed means exemplified by serial or parallel interfaces or Ethernet,the procedures of FIGS. 5 to 10 can be implemented so long as thecommunication means is means that can be equipped with the communicationprotocol described in the first embodiment.

The first embodiment illustrates an example in which a master agent isplaced in a network controller and a subagent is disposed in a printercontroller. However, an arrangement can be adopted in which the masteragent is placed in the printer controller and the subagent is placed inthe network controller. In such case a packet that has been transmittedfrom the SNMP manager to a network device would be delivered to theprinter controller as is via the network controller. In such case,therefore, it would be necessary for the network controller to have thefunctions of the subagent of the first embodiment and a function thatallows an SNMP packet to pass between the SNMP manager and printercontroller as is.

In the first embodiment, the master agent and subagent have controlmodule structures that differ from each other. However, they can beimplemented by exactly the same control structures. In such case theagent that analyzes a request for network management information andsends network management information to the network information managerwould function as the master agent, and the other agent would functionas a subagent.

The first embodiment illustrates an example in which the invention isimplemented by one subagent and one master agent. However, it ispossible to adopt an arrangement in which N-number (two or more) ofsubagents exist with respect to one master agent.

FIG. 11 is a diagram showing an arrangement having one master agent andN-number of subagents.

As shown in FIG. 11, a master agent 1101 separates a subagent SNMPpacket and transmits it to a first subagent 1102. If the first subagent1102 detects in the variable binding of the received packet a variablethat is not being managed by the MIB database of the first subagent1102, then the latter stores the position of this variable and separatesthe variable from the packet. The deleted variable and its value areseparated and constructed as a second subagent SNMP packet in a firstsubagent packet generator. This packet is transmitted to a secondsubagent 1103. Similar control is executed from an (N−1)th subagent 1104to an Nth subagent 1105. The Nth subagent 1105 processes a receivedrequest (packet), generates a packet containing the results of thisprocessing and sends the packet back to the (N−1)th subagent 1104. Thelatter reconstructs a packet, which is to be sent back to the (N−2)thsubagent, from a packet containing results of processing executed by itsown agent and the packet sent back from the N-th subagent, and sends thereconstructed packet back to the (N−2)th subagent. This control iscarried out by each subagent and the master agent 1101. As a result, themaster agent can acquire the results of processing by all of theN-number of subagents and by the master agent and can respond to theSNMP manager. Thus, control for responding with network managementinformation can be executed in distributed fashion by N-number (two ormore) of subagents.

Thus, messages are caused to flow from an upstream agent to a downstreamagent and variables to be processed are successively extracted andprocessed. Conversely, processed results are caused to flow fromdownstream to upstream while being successively reconstructed, whereby amessage packet received from an SNMP manager is eventually processed andthe results can be provided as a response.

In the arrangement of FIG. 11, all of the subagents have the functionsof the master agent of the first embodiment. However, since the encodingof transmit packets and the decoding of receive packets are not carriedout, these functions are unnecessary. Further, the master agent also hasfunctions similar to those of the first embodiment. Accordingly, themaster agent and subagent shown in FIG. 11 differ from each otherfunctionally depending upon whether the encoding of a transmit packet orthe decoding of a receive packet is performed.

Further, since the Nth agent does not have an agent downstream, it doesnot require a packet separating/reconstructing function, though there isno harm is providing it with such a function. The reason for this isthat since the SNMP manager keeps track of the MIB that each networkdevice manages by an MIB view, the SNMP manager does not in principlespecify a variable name not being managed by a device. If processing isexecuted correctly, therefore, there should be no unmanaged variablesleft in the packet received by the Nth agent. Further, if provisions areto be made for a case where a variable not being managed by the Nthagent does remain in a packet, it will suffice to decide on a processingprocedure that will give an error indication in a case where there is notransmission destination for the packet.

In such case the first embodiment would take on a form in which the1^(st) to the (N−1)th subagents have been removed from FIG. 11, leavingthe master agent and the N-th subagent. Further, the controllers havingagents are serially connected, though it is not required that they beelectrically and physically serial. If the connection between agents isserial logically, there is no restriction as to the mode of theelectrical or physical connection.

The present invention can be applied to a system constituted by aplurality of devices (e.g., a host computer, interface, reader, printer,etc.) or to an apparatus comprising a single device (e.g., a copier orfacsimile machine, etc.).

Furthermore, it goes without saying that the object of the invention isattained also by supplying a storage medium storing the program codes ofthe software, which is illustrated in FIG. 5 and FIGS. 7 to 10, forperforming the functions of the foregoing embodiments to a system or an.apparatus, reading the program codes with a computer (e.g., a CPU orMPU) of the system or apparatus from the storage medium, and thenexecuting the program codes. In this case, the program codes read fromthe storage medium implement the functions of the embodiments and thestorage medium storing the program codes constitutes the invention.Furthermore, besides the case where the aforesaid functions according tothe embodiments are implemented by executing the program codes read by acomputer, it goes without saying that the present invention covers acase where an operating system or the like running on the computerperforms a part of or the entire process in accordance with thedesignation of program codes and implements the functions according tothe embodiments.

It goes without saying that the present invention further covers a casewhere, after the program codes read from the storage medium are writtenin a function expansion card inserted into the computer or in a memoryprovided in a function expansion unit connected to the computer, a CPUor the like contained in the function expansion card or functionexpansion unit performs a part of or the entire process in accordancewith the designation of program codes and implements the function of theabove embodiment.

In a case where the present invention is applied to the above-describedstorage medium, program code corresponding to the flowcharts (shown inFIG. 5 and in FIGS. 7 to 10) described earlier would be stored on thestorage medium.

Thus, in accordance with the present invention as described above, amanagement information database originally possessed by a networkcontroller can be dispersed among connected peripheral devices. Thismakes it unnecessary for the network controller to be equipped with alarge-capacity memory.

Further, a network controller and a peripheral device connected theretocan communicate information by using a protocol identical with acommunication protocol specified between a network information managerand the network controller. It is therefore no longer necessary toprovide the network controller with a plurality of protocol controlmeans.

Furthermore, in a case where a peripheral device is added to a networkcontroller anew, the network controller can be updated if the peripheraldevice is equipped with a subagent for managing its own networkmanagement information.

As many apparently widely different embodiments of the present inventioncan be made without departing from the spirit and scope thereof, it isto be understood that the invention is not limited to the specificembodiments thereof except as defined in the appended claims.

1. A network controller for managing a plurality of peripheral devices,and constructed for connection to a communication line, comprising:receiving means for receiving a data packet from a management apparatusvia the communication line; connecting means for connecting the networkcontroller to the plurality of peripheral devices; identifying means foridentifying a first variable for receipt by the network controller andrespective variables with regard to each of the plurality of connectedperipheral devices, to be sent to and processed by respective peripheraldevices, in the data packet which has been received by said receivingmeans; constructing means for constructing a first data packet with thefirst variable and a second data packet with the respective variables tobe processed by the respective peripheral devices of the plurality ofconnected peripheral devices; sending means for sending the second datapacket with the respective variables to the respective peripheraldevices and causing the respective peripheral devices to process thesent data packet; processing means for processing the first data packetwith the first variable; and transmitting means for transmitting aresponse data to the management apparatus which contains a result ofprocessing the first data packet performed by said processing means,wherein the response data sent by the transmitting means to themanagement apparatus further contains a result of processing the seconddata packet performed by the respective peripheral devices to which thesecond data packet was sent by said sending means.
 2. The networkcontroller according to claim 1, further comprising holding means forholding information relating to the network controller, wherein saidprocessing means processes the first data packet using the informationheld by said holding means.
 3. A method of controlling a networkcontroller for managing a plurality of peripheral devices, wherein thenetwork controller is constructed for connection to a communicationline, the method comprising: a receiving step of receiving a data packetfrom a management apparatus via the communication line; a connectingstep of connecting the network controller to the plurality of peripheraldevices; an identifying step of identifying a first variable for receiptby the network controller and respective variables with regard to eachof the plurality of connected peripheral devices, to be sent to andprocessed by respective peripheral devices, in the data packet which hasbeen received at said receiving step; a constructing step ofconstructing a first data packet with the first variable and a seconddata packet with the respective variables to be processed by therespective peripheral devices of the plurality of connected peripheraldevices; a sending step of sending the second data packet with therespective variables to the respective peripheral devices and causingthe respective peripheral devices to process the sent data packet; aprocessing step of processing the first data packet with the firstvariable; and a transmitting step of transmitting a response data to themanagement apparatus which contains a result of processing the firstdata packet performed in said processing step, wherein the response datasent in said transmitting step to the management apparatus furthercontains a result of processing the second data packet performed by therespective peripheral devices to which the second data packet was sentin said sending step.
 4. The method according to claim 3, furthercomprising a holding step of holding information relating to the networkcontroller, wherein said processing step processes the first data packetusing the information held at said holding step.
 5. A non-transitorycomputer-readable storage medium storing a computer program forimplementing control in a network controller for managing a plurality ofperipheral devices, wherein the network controller is constructed forconnection to a communication line, said program comprising: a receivingstep of receiving a data packet from a management apparatus via thecommunication line; a connecting step of connecting the networkcontroller to the plurality of peripheral devices; an identifying stepof identifying a first variable for receipt by the network controllerand respective variables with regard to each of the plurality ofconnected peripheral devices, to be sent to and processed by respectiveperipheral devices, in the data packet which has been received at saidreceiving step; a constructing step of constructing a first data packetwith the first variable and a second data packet with the respectivevariables to be processed by the respective peripheral devices of theplurality of connected peripheral devices; a sending step of sending thesecond data packet with the respective variables to the respectiveperipheral devices and causing the respective peripheral devices toprocess the sent data packet; a processing step of processing the firstdata packet with the first variable; and a transmitting step oftransmitting a response data to the management apparatus which containsa result of processing the first data packet performed in saidprocessing step, wherein the response data sent in said transmittingstep to the management apparatus further contains a result of processingthe second data packet performed by the respective peripheral devices towhich the second data packet was sent in said sending step.
 6. Thenon-transitory computer-readable storage medium according to claim 5,wherein said program further comprises a holding step of holdinginformation relating to the network controller, wherein said processingstep processes the first data packet using the information held at saidholding step.
 7. A network device constructed for connection to acommunication line and including a plurality of peripheral processingunits and a network controller for managing the plurality of peripheralprocessing units, wherein said network controller comprises: firstreceiving means for receiving a data packet from a management apparatusvia the communication line; connecting means for connecting the networkcontroller to the plurality of peripheral processing units; identifyingmeans for identifying a first variable for receipt by the networkcontroller and respective variables with regard to each of the pluralityof peripheral processing units, to be sent to and processed byrespective peripheral processing units, in the data packet which hasbeen received by said first receiving means; constructing means forconstructing a first data packet with the first variable and a seconddata packet with the respective variables to be processed by therespective peripheral processing units of the plurality of connectedperipheral processing units; sending means for sending the second datapacket with the respective variables to the respective peripheralprocessing units, and for causing said respective peripheral processingunits to process the sent data packet; first processing means forprocessing the first data packet with the first variable; andtransmitting means for transmitting a response data to the managementapparatus which contains a result of processing the first data packetperformed by said first processing means, wherein the response data sentby the transmitting means to the management apparatus further contains aresult of processing the second data packet performed by the respectiveperipheral processing units unit to which the second data packet wassent by said sending means, and wherein each peripheral processing unitcomprises: a second receiving means for receiving the second data packetwith the respective variables constructed by the constructing means; anda second processing means for processing the second data packet, whichhas been received by said respective receiving means, upon referring toa database holding information relating to the respective peripheralprocessing unit.
 8. The network device according to claim 7, furthercomprising holding means for holding information relating to the networkcontroller, wherein said first processing means processes the first datapacket using the information held by said holding means.